The Venus Transit by SFAA remote reporter Bob Berta

by Robert Berta

One of the advantages of my recent retirement move to Michigan from California was the fact that I would be able to see the Venus transit of the Sun on June 8th. I live about 30 miles north of Detroit and am now a member of two clubs here...the Warren Amateur Astronomers...and the Oakland Astronomy Club (the last is named after the county it resides in)....and still a member of the San Francisco Amateur Astronomers. Luckily both clubs have observatories relatively close to me...one is only 6 miles from my house and has both a domed observatory housing a 12.5" classical cassegrain on a big German mount as well as a shed that houses a 22" DOB. It is located in a big city park that is about the size of GG Park. While the park is locked up at night normally...members have access to the keys to get into the park and turn off all the security lighting and have free use to both the scopes and observatories as well as the grounds to setup their own scopes. That was the site that 5 of us elected to setup this morning to view the transit. Other members went to different public sites to share the views.

The weather was gloriously clear and steady this morning giving tack sharp images through my TV -85 APO equiped with a Coronado Halpha 60mm filter setup. We also had another 80mm scope setup for white light viewing and 35mm photography. The sun came up above the horizon around 6:00 and we had to wait a few minutes for it to get above the low trees in that direction (about 4 degrees above the horizon). We ALL were impressed with the size of the planet as compared to the sun. We expected a tiny spot across the face requiring a telescope to see. The relative size was so large that we could easily see it naked eye through a #14 welding lens hand at 1x. By the time it got above the horizon in Michigan the planet had traveled about 1/2 way across the face. The disk was a sharp black sphere that steadily moved towards a nice flare/promience on the edge of the sun. In the same relative area there were a couple of other edge on flares (in Halpha these show up as a thin black line against the sun's disk that looks like a hair on your optics). We also saw excellent mottling and surface detail across the sun and some very small sun spots.

You may have read about a strange phenomenon that happens when the planet makes third contact (the point when the edge of the planet first touches the edge of the visible sun on its move out of the sun. I believe this phenomenon is due to refraction but I would have to go back and review past articles on the subject. In any case all of us were able to detect this effect which is a subtle deformation of the planet disk into a tear drop or bulged shape for a very short time. Needless to say the views through my Halpha setup were the most popular and while the white light scopes got little use...one was setup with a 35mm camera so we are hoping for some nice pictures once the film is developed.

As the planet moved out of the solar sphere the last contact is known as 4th contact...the travel from 3rd to 4th contact was easily the one we all enjoyed the most....by this time the sun was high enough to yield the sharpest and contrastiest images through the scope and revealed the flares and surface detail. While the flares and promenences weren't quite as prevalent as they had been the last few days...they were still there just enough to make this event a very memorable one.

So at the end of our viewing we all made plans to do it again in 8 years for the return visit...and with a bit of luck something like 122 years after that for the next one ;-)

My good friend and SFAA past member Bob Naeye has been writing to me from Iran about his experiences there and coverage of the transit for S&T magazine. In addition the president of the Warren club here went to Greece to view the transit. It will be interesting to hear how their viewing went compared to what I saw from the US.

Bob Berta
San Francisco Amateur Astronomers

Posted on sf-bay-tac Jun 08, 2004 09:05:57 PT
Converted by report.pm 1.1 Jul 12, 2004 21:54:45 PT